The full shortcode is [bigContact form=on appointment=on phones=on emails=on hours=on map=on]. If you only need the form then you can use [bigContact form=on].

The shortcode generator builds the short code and inserts it in a post/page. To enable it check “Big Contacts” from the Screen Options of the edit page. A new metabox will appear on the page. Just check the components of the form you need and click “Insert into page.”

There is more on this on the plugin page under Publishing at the bottom of the page.